ML20238C627

Forwards Relief Request Re Volumetric Exam of Various Cast Stainless Steel Welds in Reactor Coolant Loops.Relief Request Being Included in Inservice Insp Program Plan

ML20238C627
Person / Time
Site:	Byron
Issue date:	09/01/1987
From:	Ainger K COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
3540K, TAC-60703, NUDOCS 8709100259
Download: ML20238C627 (26)

Text

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'N Commonwealth Edison k.i /. One First N;$onal Plaza, Chic"go, Illinois

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JAddress Rip ly to: Post Office Box 767

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'v' Nd Chicago, Illinois 60690 0767 l

September 1, 1987 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Byron Station Unit 1 Inservice Inspection Program TAC No. 60703 NRC Docket No. 50-454 Gentlemen:

Enclosed with this letter'are requests for relief from the examination requirements of ASME Code Section XI.

These relief requests pertain to the volumetric examination of various cast stainless steel welds in the reactor coolant loops of Byron Unit 1.

These relief requests are being included in the Inservice Inspection Program Plan for. Byron Station Unit 1.

Please direct any questions regarding this matter to this office.

Very truly yours, K. A. Ainger Nuclear Licensing Administrator Enclosure I

cc: Byron Resident Inspector NRC Region III office 3540K g91002 870901 b

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Revision 2 RELIEF REQUEST NR-4 1.

SYSTEM: Reactor Coolant 1

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NUMBER OF ITEMS: 8 l

Cast Stainless Steel SA-351-CF8A (Elbow) to Cast Carbon Steel SA-216 GR-WCC (Nozzle) l Line Number Weld Number Attachment Number 1RC01AA-29 F2 1&2 i

1RCO2AA-31 F1 1&2 1RC01AB-29 F2 1&2 1RCO2AB-31 F1 1&2 1

1RC01AC-29 F2 1&2 1RCO2AC-31 F1 1&2 1RC01AD-29 F2 1&2 1RCO2AD-31 F1 1&2

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3.

ASME CODE CLASS:

1 4.

ASME CODE SECTION XI REQUIREMENTS: Subsection IWB, Table IWB-2500-1.

Examination Category B-F Item B5.70 requires surface and volumetric examination of the regions described in Figure IWB-2500-8 for Steam Generator nozzle-to-safe end butt welds > 4 in, nominal pipe size.

Examinations shall be conducted on all nozzle-to-safe end butt welds each inspection interval.

In addition, examination Category B-P, Item B15.30 requires a system leakage test, (IWB-5221) each refueling outage for Steam Generator pressure retaining boundaries.

Ultrasonic examination requirements from Mandatory Appendix III, Article III-4000 requires examination for:

a.

Reflectors parallel to the weld seam.

The examination shall be performed using a sufficiently long examination beam path to provide coverage of the required examination volume in two beam path directions. The examination shall be performed from two sides of the weld, where practicable, or from one side of the weld, as a minimum.

b.

Reflectors transverse to the weld seam The angle beam examination for refl< actors transverse to the weld shall be performed on the weld crown on a single scan path to examine the weld root by one-half V-path in two directions along the weld.

, In conformance with IWA-2232, reflectgrs which produce a response greater than 50% of the reference level shall be recorded. The size of reflectors shall be measured between points which produce amplitudes equal to 100*4 of the reference level.

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i Ravision 2 5.

Basis for Relief: The welds listed above are cast austenitic stainless steel (SA-351-CF8A)-to-cast carbon steel (SA-216 GR-WCC) with stainless steel buttering. Ultrasonic examination of the required volume from Figure IWB-2500-8, (lower 1/3t, extending 1/4 in beyond both sides of the weld) cannot be inspected in accordance with Mandatory Appendix III requirements due to the high attenuating properties encountered in the cast austenitic stainless steel. Neither the one half V-path technique from the elbow side of the weld, nor the full V-path technique from the nozzle side of the weld provide sufficient resolution and/or penetration of the cast austenitic stainless material.

6.

ALTERNATE TEST METHOD: Ultrasonic examination of the lower 1/3t, extending 1/4 in. into the cast austenitic stainless steel, failed to produce an adequate signal to noise ratio, essential to reporting and/or sizing. Presently, conventional radiography is not a viable inservice examination technique as background radiation will increase over plant life and is likely to cause the film to fog. This fogging would reduce the resolution of any defects.

It is, therefore, proposed that the ultrasonic examination of these welds be performed as follows:

a.

Examinations will be performed on the required volume from the nozzle side of the weld employing the one half V-path technique q

for reflectors parallel to the weld. The heat affected zone on i

I the nozzle side, the weld metal and, to the maximum extent practical, the heat affected zone on the cast side will be examined.

b.

Best-effort examinations of the heat affected zone on the cast side of the weld will be performed from the cast side of the weld employing a one half V-path, refracted, longitudinal wave technique for reflectors parallel to the weld.

It is expected that this technique will be capable of penetrating ultrasound to the weld I.D. and detecting large flaws (25% or greater through-wall dimension) in the cast material.

c.

Best-effort examinations will be performed on the required volume in two directions along the weld employing the one half V-path technique for reflectors transverse to the weld; d.

Recording and/or evaluation of reflectors from the cast austenitic stainless steel volume shall be performed for reflectors equal to or greater than 50% of the reference level obtained by maximizing the tip signal response of the 50%, 25% and 10% deep I.D. notches in the calibration block. Note, recording and/or evaluation of reflectors from the nozzle material and/or weld metal shall be completed in accordance with IWA-2232.

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m Revision 3 One hundred percent completion of the examinations on all of the welds listed above is not required until the end of the first 120 month inspection interval, although a minimum of 16% must be completed by the end of the first 36 month inspection period.

Since new and more advanced techniques are continuously being developed, it'is likely that a technique for the examination of the required volume will be available prior to the completion of the first 120 month inspection-interval. When such techniques become available, they will be evaluated for practicability.

7.

JUSTIFICATION:

In that cast austenitic stainless steels are extremely tough and resistant to intergranular stress corrosion cracking, leakage long before complete failure is virtually certain. Leakage from the Reactor Coolant System is checked each refueling outage via a VT-2 visual examination.

In addition to the system leakage test, leakage within the containment will be monitored by two (2) remote methods.

First, leakage from within the containment will flow into the weir box of the containment sump. Within this weir box there is a level indicator capable of detecting a 1 gallon per minute leak within an hour of reaching the sump.

In addition to the level indicator there are sump pump run time totalizers which measure pump run time and are capable of detecting a 1 gallon per minute leak.

The second method utilizes a containment radiation monitoring system capable of detecting a 1 gallon per minute leak within an hour of reaching the sump.

Additional atmospheric monitoring is provided by pressure, temperature, and humidity monitors. All atmospheric monitors are monitored in the main control room.

By implementation of the proposed inspections, the information provided by the leakage detection system, and the high resistance of cast austenitic stainless steel to stress corrosion cracking, an adequate level of structural integrity for these welds will be assured for plant operations.

8.

APPLICABLE TIME PERIOD:

Relief Will be required for the first 120 month inspection interval.

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RELIEF REQUEST NR-5 1.

SYSTEM: Reactor Coolant 2.

NUMBER OF ITEMS:

9 Cast Stainless Steel SA-351-CF8A (Elbow) to Stainless Steel SA-376 GR. 304N (Pipe)

Line Number Wald Number Attachment Number IRC02AA-31" J1,J2,J3,&J7 1&2 1RC03AA-27.5"-

J10 1&2 Cast Stainless Steel SA-351-CF8 (Pump) to Stainless Steel SA-376 GR. 304N (Pipe)

Line Number Weld Number Attachment Number 1RC03AA-27.5" J1 1&3 Cast Stainless Steel SA-351-CF8M (Valve) to Stainless Steel SA-376 GR. 304N (Pipe)

Line Number Weld Number Attachment Number 1RC01AA-29" J3 1&4 1RC03AA-27.5" J4 & J5 1&4 3.

ASME CODE CLASS: 1 l

4.

ASME CODE SECTION XI REQUIREMENTS: Subsection IWB, Table IWB-2500-1, j

Examination Category B-J, Item B9.ll requires surface and volumetric examination of the regions described in Figure IWB-2500-8 for circumferential welds > 4 in. nominal pipe size. Examinations shall be I

conducted on all terminal end welds to vessels, high stress welds, dissimiliar metal welds, and additional welds to equal 25% of the welds in the reactor coolant piping system each inspection interval.

In addition, Examination Category B-P, Item B15.50 requires a system leakage test, (IWB-5221) each refueling outage for piping pressure retaining boundaries.

Ultrasonic examination requirements from Mandatory Appendix III, Article III-4000 requires examination for:

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The examination shall be performed using a sufficiently long examination beam path to provide coverage of the required examinationvolumeinpwobeampathdirections. The examination shall be performed from two sides of the weld, where practicable, or from one side of the weld, as a minimum.

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j In conformance with IWA-27.32, reflectors which produce a response I

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BASIS FOR RELIEF; The welds' listed above are cast austenitic stainless j

steel (componenti to stainless steel'(pipe). Ultrasonic examination of the required volume from Figure IE2500-8, (lower 1/3t extending 1/4 in. risyond both sides of the wald) cannot be inspected in accordance with Mandatory Appendix III requirements due to the high attenuating properties' encountered in the cast austenitic stainless steel. Neither the one half V-path technique from the coinponent side of the weld, nor the full V-path technique from the pipe side of the weld provide sufficient resolution and/or penetration of the cast austenitic stainless steel.

l 6.

JLTERNATE TEST METHOD: Presently, conventional radiography is not a viable inservice examination technique as background radiation will increase over plant life and is likely to cause the film to fog. This fogging would reduce the resolution of any defects.

It is, therefore, proposed that the ultrasonic examination of these welds be performed as follows:

a.

Examinations will be performed on the required volume from the J

pipe.s'tde of the wold employing a one half V-path technique for reflectors paralici to the weld.

The pipe side heat affected zone, the weld rettl and, to the maximum extent practical, the heat affected voce ca the cast side will be examined, l

b.

Best-effort examina.tions of the heat affected zone on the cast side of the weld will be performed from the cast side of the weld employing a one half;V-path, refracted, longitudinal wave 3

technique for reflecton paralle'. to the weld.

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JUSTIFICATION:

Ta that cast austenit!4 4tainless steels are extremely f

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long before complete failure is virtually certain. beaktge from the l

Reactor Coolant Syst s is checked each refueling outage via a VT-2 examination.

In additior, to the system leakage test, leakage within

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the containment will ue mo?.itored by two (2) remote methods.

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1echgi fton withm 'he contcinMnt will flow into the sit box cf the con ginment sump W'ithin thin weir box there is a level indicator esyble of d teer ing a 1,ga:!1on por minute.lpak wit:11n an hour of reuhing the sug.

In addition to the level indicator there are sump pty run time totalizerer which measure pump rjn time and are capable of de h ting a 1 gallon per minute leak.

The second metnid utilizes a et.ntainment radiation monitoring system I

capatino.71 detecting a 'l galloh per minute ' Leak within an ho!.>r of reachi:tg the sump. ' Additional atmor,theric inonitoring is prqvided by pressure, t:emperature, md humidity monitors. hil atmospheric monitor.;

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'are moniteTed in 'the main control room.

By, implementation of 'th's proposed insteed.ons, the Information' provided by the leauage detection

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8.

3PJHCABLE MM1 PERIOD:

Relief will be regt.isd for the first 120 non',.1 inspection interval.

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RELIEF REQUEST NR-6 1.

SYSTEM: Reactor Coolant 1

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NUMBER OF ITEMS: 2 Cast Stainless Steel SA-351-CF8A (Elbow) to Cast Stainless Steel SA-351-CF8 (Pump)

Line Number Weld Number Attachment Number 1RC02AA-31" J8 1&2 Cast Stainless Steel SA-351-CF8A (Elbow)

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to Cast Stainless Steel SA-351-CF8M (Valve)

Line Number Weld Number Attachment Number IRC01AA-29" J4 1&3 3.

ASME CODE CLASS:

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4.

ASME CODE SECTION XI REQUIREMENTS: Subsection IWB, Table IWB-2500-1, Examination Category B-J, Item B9.ll requires surface and volumetric examination of the regions described in Figure IWB-2500-8 for l

circumferential welds > 4 in nominal pipe size. Examinations shall be conducted on all terminal end welds to vessels, high stress welds, dissimiliar metal welds, and additional welds to equal 25% of the welds in the reactor coolant piping system each inspection interval.

In addition, examination Category B-P, Item B15.50 requires a system leakage test, (IWB-5221), each refueling outage for piping pressure retaining boundaries.

Ultrasonic examination requirements from Mandatory Appendix III, Article III-4000 requires examination for:

a.

Reflectors parallel to the weld seam.

The examination shall be performed using a sufficiently long examination beam path to provide coverage of the required examination volume in two beam path directions. The examination shall be performed from two sides of the weld, where practicable, or from one side of the weld, as a minimum.

b.

Reflectors transverse to the weld seam The angle beam examination for reflectors transverse to the weld shall be performed on the weld crown on a single scan path to examine the weld root by ona-half V-path in two directions along the weld.

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Rsvision 2 In conformance with IWA-2232, reflectors which produce a response greater than 50% of the reference level shall be recorded. The size of reflectors shall be measured between points which produce amplitudes equal to 100% of the reference level.

5.

BASIS FOR RELIEF: The welds listed above are cast austenitic stainless steel (component) to cast austenitic stainless steel (component).

Ultrasonic exaraination of the required volume from Figure IWB-2500-8, (lower 1/3t extending 1/4 in. beyond both sides of the weld) cannot be inspected in accordance with Mandatory Appendix III requirements due to the high attenuating properties encountered in the cast 'Austenitic stainless steel. Neither the one half V-path technique nor the full V-path technique from either side of the weld provide sufficient resolution and/or penetration of the cast austenitic stainless steel.

6.

ALTERNATE TEST METHOD: No ultrasonic transducer as of this writing can effectively penetrate the required examination volume, (lower 1/3t, extending 1/4 in. on both sides of the weld), with meaningful and interpretable results. In addition, conventional radiography is not a viable inservice examination technique due to high background radiation.

It is therefore proposed that the ultrasonic examination of these welds be performed as follows:

a.

Best-effort examinations will be performed on the required weld volume utilizing the refracted longitudinal wave with the one half V-path technique. The weld metal and both sides of the weld will be examined for reflectors parallel to the weld. It is expected that this technique will be capable of penetrating ultrasound to the weld I.D. and detecting large flaws (25% or greater through-wall dimension) in the cast material.

b.

Best-effort examinations will be performed on the required volume circumferentially in two directions along the weld employing the one half V-path technique for reflectors transverse to the weld.

c.

Recording and/or evaluation of reflectors will be equal to or greater than 50% of the reference level obtained by maximizing the tip signal response of the 50%, 25% and 10%

deep I.D. notches in the calibration block. Note, ASME Section XI required sensitivity will not be obtained.

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1 Revision 2 Ons hu'ndred percent completion of the examinations on all of the' welds selected'for-examination is not required until the end'of-the'first 120 month ~ inspection interval, although a minimum of 16% must be completed H

by the end of the first 36 month inspection period. Since new and more

~

' advanced' techniques are continuously being developed, it is likely that

'a new technique for the examination of the required volume will be

.available prior.to the completion ~of the first 120 month inspection interval. When such techniques become available, they will be evaluated for practicability.

7.

JUSTIFICATION:

In that' cast austenitic stainless steels are extremely tough and resistant to intergranular stress corrosion cracking, leakage long before complete failure is virtually-certain. Leakage from the Reactor Coolant System is checked each refueling outage via a VT-2

-examination. In addition'to'the system leakage test, leakage within.

the containment will be monitored by two (2) remote methods.

First, leakage from within the containment will flow into the weir box of the containment sump. Within this weir box there is a level indicator capable of detecting a 1 gallon per minute leak within an hour of reaching the sump'.

In addition to the level indicator there are sump pump.run time totalizers which measure pump run time and'are capable of detecting a 1 gallon per minute leak.

The second method utilizes a containment radiation monitoring system capable of detecting a'1' gallon per minute: leak within an hour of reachihg the sump. Additional atmospheric monitoring'is provided by pressure, temperature, and. humidity monitors. All atmospheric monitors are monitored in the main control room.

By implementation of the proposed inspections, the information provided by the leakage detection system, and'the high resistance of cast austenitic stainless steel to stress corrosion cracking, an. adequate level of structural integrity for!these welds will'be assured for plant operations.

8.

APPLICABLE TIME PERIOD:

Relief will be required for the first 120 month inspection interval.

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RELIEF REQUEST NR-7 l.

SYSTEM: Reactor Coolant 2.

NUMEER OF ITEMS:

1 Cast Stainless Steel SA-351-CF8A (Elbcw) to Stainless Steel SA-182 GR-F316 (Safe End)

Line Number Weld Number Attachment Number 1RC03AA-27.5" Jll 1&2 i

3.

ASME CODE CLASS:

1 4.

ASME CODE SECTION XI REQUIREMENTS: Subsection IWB, Table IWB-2500-1, Examination Category B-J, Item B9.ll requires surface and volumetric examination of the regions described in Figure IWB-2500-8 for circumferential welds > 4 in nominal pipe size. Examinations shall be conducted on all terminal end welds to vessels, high stress welds, dissimiliar metal welds, and additional welds to equal 25% of the welds in the reactor coolant piping system each inspection interval.

In addition, examination Category B-P, Item B15.50 requires a system leakage test, (IWB-5221) each refueling outage for piping pressure retaining boundaries.

Ultrasonic examination requirements from Mandatory Appendix III, Article III-4000 requires examination for:

a.

Reflectors parallel to the weld seam.

J The examination shall be performed using a sufficiently long examination beam path to provide coverage of the required examination volume in two beam path directions. The examination shall be performed from two sides of the weld, where practicable, or from one side of the weld, as a minimum.

b.

Reflectors transverse to the weld seam The angle beam examination for reflectors transverse to the weld shall be performed on the weld crown on a single scan path to examine the weld root by one-half V-path in two directions along the weld.

In conformance with IWA-2232, reflectors which produce a response greater than 50% of the reference level shall be recorded.

The size of reflectors shall be measured between points which produce amplitudes equal to 100% of the reference level 2-68 (0334M/0041M)

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RASIS FOR RELIEF: The above listed weld is capt austenitic atQinlegs steel (SA-351-CF8A)-to-stainless steel (SA-182 GR-F316) safe end.

Ultrasonic examination of the required volume from Figure IWB-2500-8, (lower 1/3t extending 1/4 in, beyond both sides of the weld) cannot be inspected in accordance with Mandatory Appendix III requirements due to the high attenuating properties encountered in the cast austenitic stainless steel. Nai+.her the one half V-path technique from the elbow side of the weld, nor the full V-path technique from the safe end side of the weld provide suffi: lent resolution and/or penetration of the cast austenitic stainless steel.

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6.

ALTERNATE TEST METHOD: Presently, conventional radiography is not a viable inservice examination technique as background radiation will increase over plant life and is likely to cause the film to fog. This fogging would reduce the resolution of any defects.

It is, therefore, proposed that the vitrasonic examination of this weld be performed as follows:

a.

Exarainations will be performed on the required volume from the cafe-end side of the weld utilizing the refracted longitudinal wave with the one, half V-path technique. The safe end heat affected zone, the weld metal, and, to the maximum extent practical, the elbow side heat affected zone, will be examined for reflectors parallel to the weld.

b.

Best-effort examinations of the heat affected zone on the cast side of the weld will be performed from the cast side of the weld employing a one half V-path, refracted, longitudinal wave technique for reflectors parallel to the weld. It is expected that this technique will be capable of penetrating ultrasound to the weld I.D. and detecting large flaws (25% or greater through-wall dimension) in the cast material.

c.

Best-effort examinations will be performed on the required volume in two directions along the weld employing the one half V-path technique for reflej: tors trtansverse to the weld.

d.

Recording and/or evaluation of reflectors from the cast austenitic stainless steel volume shall be performed for reflectors equal to or greater than 50% of the reference level obtained by maximizing V

the tip signal responne of the 50%, 25% and 10% deep I.D. notches in the calibration block. Note, recording and/or evaluation of

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reflectors from the safe end material or weld metal shall be completed in accordance with IWA-2232.

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One hundred percent completion of the examinations on all of the welds selected-for examination is not required until the end of the first 120 morah inspection interval, although a minimurs of 16% must be qompleted J

by the end of the first 36 month inspection period. Since new and more j

' advthced techniquts are continuously being developed. "it is likely that A

a 'ts.w :te:hnique for the examination of the required volurn, will be i

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JUSTTPICATION:_ In that cast austenitic stainless 5tselu are extremely p

t i, tougtJ m d resista^t to intergranular stress'corrosicq cracking, leakarte Reactor.C.b[lant system is checked each refupling. outage.

long btTore complete failure is virtually certeiji. Leakage within the;

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In'nddition, Nd to this (edkage test, leakage within,the c6ntainment will be moaltored

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by two (2);remete methods.

First, leakaga (rom within the contair. ment will flow into the weir) box of the contaf.nment sump. Within this weir.

borqthere fat a level ir.dicator capable of detecting a 1 gallon per minute leak within an heur of. reaching the sump.

In addition to the level indicator thers arn nump pump run time totalizers which mqasui'e peap run time and c4.eble of detectir.g a 1 gg11on per minute leak.

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The second method utilizes a containitent radiation monitoring system capable of detecting a 1 gallen per minute leak within an hour of reaching the sump. Additional atmospheric monitoring is provided by pressure, temperature, and humidity monitors. All atmospheric monitors

~are monitcgedt in the main control room.

By ittplementation of the proposed inspections, the information grovided by,the leakage detection system, and $be high resistance of cast austenitic stainless steel to '

streer corrosisn cracking, an adequato Ic.yal of structural integrity 3

for thsse weldafwill be assured for piant operations.

8.

APPLICAPLE 11M3 PCRICp Relief will b.e required for'the first 120 month inspection interval.

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